1. Field of the Invention
The present invention relates to making trusses for home and office building construction. More particularly, the present invention relates to conveyor systems for assembling uniform, finished trusses.
2. Discussion of Background
To form support for a pitched roof for buildings and homes, framework structures called trusses are installed on the tops of the walls of the buildings to hold the roofing at the desired angle. The trusses, usually made of wood, comprise one or more bottom boards that will be oriented perpendicularly to the walls, two angled top boards, and several boards, called webbing, supporting the top boards from the bottom boards. The arrangement of boards is fixed by nailing connector plates, which are flat metal plates with spike-like perforations formed therein, to the sides of two or more boards where those boards intersect. The connector plates hold the various components of the trusses together in their appropriate spaced relation.
Although there are apparatus for assembling trusses for homes and office buildings, most truss assembling is still done either at the job site or by forming an ad hoc jig on a large table and making each truss using that jig. In the former case, the trusses may not be as uniform as would be expected if built under more controlled conditions. In the latter case, the time spent assembling the ad hoc jig is approximately one-third of the overall time to assemble the trusses. Furthermore, if a mistake is made in assembling the jig, it will be propagated through all the trusses built therewith.
There are several apparatus for facilitating the assembly of trusses. In particular, there are several using conveyor belts that move slats on which the trusses are assembled. See for example, the truss assembly jig of Adams as described in U.S. Pat. No. 3,925,870, the apparatus of Tison for forming wood trusses described in U.S. Pat. No. 4,252,058, and the truss assembly apparatus of Harnden as disclosed in U.S. Pat. No. 4,943,038. See also Templin's apparatus and Jureit, et al's apparatus in U.S. Pat. No. 3,667,379 and U.S. Pat. No. 3,443,513, respectively. All of these may streamline the production of trusses but none avoids the fundamental problem of the time to set up the truss jig on the conveyor. There remains a need for shortening this set up time.